Tnetter is right.

Fat makes it moist. Did anyone see the Fannie Farmer meal they fixed on PBS? She wrote cookbooks in the late 1800s and they decided to fix a holiday meal the way they did back then, even using the same equipment. It took about 1-1/2 years to pull it together and was fascinating. Anyway, when they cooked a goose they laid strips of salt pork across the top of the goose to keep it moist (ducks are fatty - are goose? - can't imagine how wet that was). When they cooked venison they threaded pieces of salt pork all over it. It looked like something stitched. But everyone raved about the meal.